Nine decades after the disappearance of the infamous Spanish flu, its ghost is threatening again. In many countries, panicking citizens are buying drugs from uncertain sources through the internet for a disease that does not yet exist.1 In September 2005, Dr Nabarro, the World Health Organization's public health expert coordinating the response to avian influenza, told the Associated Press that a global avian influenza pandemic could kill 150 million people worldwide.2 What are the risks of a pandemic and is stockpiling antiviral drugs the best response?

How real is the risk of pandemic?

A new pandemic with a highly pathogenic influenza strain is obviously possible. But other infectious agents present similar risks—for example, an Ebola epidemic with airborne transmission, an AIDS epidemic with a much more virulent strain of HIV (superbug), or massive food poisoning such as the dioxin crisis. Airborne transmission of the extremely lethal Ebola Zaire virus might cause a devastating epidemic and is popular in both fiction and (alleged) non-fiction. The HIV superbug appeared in February 2005 in New York as a virus with multiple mutations, multiple drug resistance, and a rapid course of infection, but in only one person. The case served to rekindle the US public's fear after interest in AIDS had been waning because of Iraq.

In the Belgian dioxin crisis, dioxins got mixed up in the food chain, causing levels of exposure to dioxins similar to those in the 1980s.3 The crisis fell conveniently (for the political opposition) just before an election. Competitors in the highly regulated European food market saw their chance to increase market shares. Seven million chicken and 60 000 pigs were slaughtered. Not one person has been detected with any observable consequence of dioxin poisoning.

Perception of risk

In a global world with global media coverage and competition for sensational news, any hypothetical doomsday scenario that …

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